Applications directed to the processing of gases by plasma treatment have been known for several decades. The field of the chemistry of processes implements them routinely to dissociate or combine molecules in gaseous or liquid phase.
The emphasis placed on research into the reverse conversion of carbon has led to the development of various reactors for which the optimization of yields has been the main motivation. The publication “Carbon Dioxide Decomposition by plasma Methods and Application of High Energy and High Density plasmas in Material Processing and Nanostructures” of 2010 in the names of Srivastava and Kobayashi reviews several of them that are used for the cracking of carbon dioxide (decomposition of carbon dioxide into oxygen and carbon). FIG. 1 of that earlier publication illustrates a conventional plasma reactor comprising an argon-based plasma torch of which the plasma jet is generated by an arc at atmospheric pressure between a central upstream electrode, in the form of a rod, and a peripheral downstream electrode, in the form of a washer chamfered at its center, the electrodes being subjected to direct current. The plasma torch is arranged at an axial end of a quartz tube delimiting a reaction chamber. The fluid to crack (carbon dioxide) is introduced radially into the device at the location of the exit from the plasma torch, at the entry into the quartz tube A drawback of such a reactor with a plasma torch is that it is relatively complex to implement and to integrate into a larger system on account in particular of the necessary presence of a store and a supply of argon for the plasma torch, and of the supply of the reactor with fluid to crack in a radial direction. For the same reasons, the arrangement of several reactors in series or in parallel is difficult.
A catalytic plasma reactor can also be seen in FIG. 1 of the 2011 publication “Conversion of carbon oxides into a membrane in a nonthermal plasma-catalytic reactor” in the names of Jwa, Mok and Lee, used for methanation of carbon dioxide (conversion of carbon dioxide into methane, by reaction with hydrogen). Such a catalytic plasma reactor comprises a quartz tube, in the center of which is placed a rod electrode acting as a discharge electrode, and externally of which is wound a copper sheet serving as ground electrode. The assembly is placed in a tubular oven adapted to heat reagents (hydrogen and carbon dioxide) and catalysts at 200-300° C. The discharge electrode is subjected to a high-voltage alternating current (between 6.5 and 10.3 kV) at a frequency of 1 kHz. Such a catalytic plasma reactor is simpler and more compact that the plasma torch reactor described above but the probability that a molecule of the fluid to convert flowing in the quartz tube passes through an arc generated between the two electrodes remains low, it being possible for arcs to occur over the whole length and whole circumference of the quartz tube in localized and random manner.